Public sector tech chiefs have lacked the technical and operational nous to deal with suppliers, resulting in the state spending billions on needlessly overcomplicated systems, according to the UK government's CTO.

Liam Maxwell, CTO for the UK government, said: "I've met people in the past in government who, with the best will in the world, were facilities managers with a Gartner subscription and then became the CIO."

And in cases where the supplier is faced with a customer with limited knowledge, suppliers can end up inflating the business problem and the solution, he said.

"There's no doubt they're going to explain to them there's a very large problem here," he said, speaking at The Economist's CIO Forum yesterday.

Suppliers will "fill that problem full of helium until people realise it's enormously difficult to deal with and end up spending literally billions of pounds on a system that has no need to be this complex," he said.

In many cases the government hopes to replace these sprawling and unnecessarily bespoke systems with an array of smaller technologies sourced from SMEs through its G-Cloud framework of cloud services.

The government is reorientating the way it approaches IT, so that it measures the cost of each transaction and it doesn't procure any IT where it doesn't understand how it fulfils a specific user need.

The lesson has been not to outsource until you're sure you understand what you're buying and why you need, said Maxwell.

Earlier this year Mike Bracken, executive director of the Government Digital Service, made similar criticisms of public sector CIOs, saying they spent their time managing contracts and not creating better services for the public.

"Many of our CIOs are performing as quasi-procurement and contract managers, rather than really driving business performance based on meeting user needs. The result? An uneven playing field, with the CIO role in government varying hugely by department and agency," he said.